The need to restrain vehicles in certain instances has long been known. For example, it has long been known that certain safety benefits can be achieved by securing a truck adjacent a loading dock during loading or unloading of that vehicle. If the vehicle were not restrained, and the truck operator were to prematurely drive away from the loading dock, loading dock personnel or equipment could be trapped on the truck and/or injured, particularly if a person was exiting or entering the truck when the vehicle pulled away from the dock.
Many solutions to this problem have been proposed. For example, motorized vehicle restraints which hook to the ICC bar of a trailer parked adjacent to a loading dock such as those sold by Rite-Hite Corp. and as disclosed in U.S. Pat. No. 4,264,259 have been very effective in addressing this problem. As another example, various forms of wheel chocks have been utilized to restrain vehicles.
Some known wheel chocks are designed for mounting beneath the surface of the parking area adjacent to the dock. Such chocks typically include a trigger located above the surface of the parking area. When a wheel contacts the trigger, the chock portion of the device rises out of the ground to form a projection in front of the truck tire.
Other prior art wheel chocks comprise chocks which either store flat or below the driveway grade, and rise up to form a projection in front of the tire. However, such chocks suffer from the disadvantage of requiring excavation of the parking area if the chock is being added to a pre-existing dock area. Some prior art chocks of the this type have also been disadvantageous in that they tend to run high relative to the trailer frame. In other words, when the chock moves out of the lowered positioned towards the chocked position, some chocks immediately rise to their full height and then run towards the tire thereby creating the risk of contact between the chock and vehicle parts or items suspended beneath the truck.
Some prior art chocks are disadvantageous in that they involve complex mechanical structures. Such structures render these chocks costly to purchase and costly to maintain. Other automatic prior art chocks have been disadvantageous in that they strike the wheel too low to adequately prevent movement of the vehicle. Traditional portable chocks also suffer from the same deficiency--i.e. striking the wheel too low--and may also be disadvantageous as nothing holds the chock in place along the driveway, and they are thus subject to sliding over the driveway surface.